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Making Mako: Behind the Walrus Audio ACS1 and R1

Making Mako: Behind the Walrus Audio ACS1 and R1

Following the 2020 release of the D1 High-Fidelity Delay, Walrus Audio introduced two new pedals in its growing MAKO family earlier this year: the ACS1 Amp + Cab Simulator and the R1 High-Fidelity Reverb.

The ACS1 Amp + Cab Simulator packs three classic amp models and six IR-based speaker cabinets into a single stereo pedal. The R1 High-Fidelity Reverb offers six studio-quality reverb programs with plenty of onboard controls to tweak to your heart's content.

We reached out to Walrus Audio's president Colt Westbrook, and general manager and lead engineer Jason Stulce, to learn more about these two new pedals, their approach to the MAKO series, and what they see in the company's future.

Let's talk MAKO. How would you describe the series, and what was your goal when creating it? Has that changed at all over the past year?

Westbrook: I think the goal for the MAKO series was really to make another.

Stulce: MAKO 'nother? 

Westbrook: Uh-huh. To make another series to put more ideas in. We have lots of ideas that are easy to put in our standard footprint pedal. Think of the Monument, Julia or Slö, something like that. Many of our ideas don't fit in that format, so the MAKO series was a catch-all for our higher-end, higher-functionality ideas.

When you look at cool stuff like the Ibanez 10 series, BOSS 200 series, or the Moog series, you see custom enclosures explicitly designed for the series. We wanted to set MAKO apart by developing our new enclosure while still doing all the other fun, cool stuff that we try to be good at.

How much was the look impacted by the more “advanced processing” idea of the pedals?

Westbrook: I wanted it to look like a tool, you know? But I wanted it to look like a really nice tool. In the original Walrus series, we wanted to have something very outwardly expressive in the artwork that matches what we perceive is happening audibly with the guitar pedal. But with the MAKO series, we wanted it to look like really nice tools. So that's kind of where we went with that. Jason probably has a lot more to say about that.

Stulce: Yeah. It's a departure from the art side of things that we're known for, but it's an effort to kind of play in both arenas with a utilitarian tool in a more sophisticated look. We always say, "Look as good as they sound," and we feel that way about MAKO. Instead of it being art-forward, it's more industrial design-forward. It broadens the palette of enclosures we can work with, and the types of ideas we can put in the products. We're for sure never going to get away from this. [Grabs Julia pedal] This is our heart and soul. That's never going away.

Can you speak to how a MAKO pedal development is different? Are there unique challenges or learning you had to do?

Stulce: The system, I would call it, that's under the hood, is far and away more technically advanced than anything we've ever done before. That doesn't necessarily mean that it's better; it just means that the parts we chose are less sort of pre-set for you, if you will. Some of these chips handle the heavy lifting for the designer with the baked-in functionality.

There are many things in the MAKO series that we just had to plow our own field to get to, digging into every little nook and cranny. Nothing in there had a starting point. It was like starting at zero, everywhere you look, from both a software and a hardware perspective. Lots of hardware iterating and design went into that to get the hardware right before we got into months and months working on software.

The ACS1 and R1 are the first products that we've ever offered remote firmware upgrades for, and so that alone is a big lift. Effects aside, the web app that we've developed, the interface to the hardware that allows the user to download firmware, that doesn't make any noise, right? That doesn't make any cool sounds, but it's a ton of work and a ton of time. I think it was really ambitious for us to take all of that on. I think we've done a pretty good job at building that ground floor, and we can continue to expand on it. I'm pretty happy with how it's turned out.

And there are so many different directions to go with this knowledge and tech, right?

Stulce: That's another cool thing. Of course, we're thinking about ways to employ with this whole firmware upgrade process, but it's not just firmware. I mean, it's kind of up to us where we take that, what features we add to it, and then what other products down the road that we tie into it. So, it doesn't necessarily have to be MAKO products that tie into that. It's built so that it's completely scalable. You could very possibly see more traditional-looking Walrus pedals having an element of firmware updating or software tweaking under the hood—things like that.

How did you settle in on which types of pedals would follow the D1?

Westbrook: We started with a delay because delay is everyone's favorite effect. And if it's not, you're probably not a guitar player. All the fuzz players cringe. "What did he just say? Did he say delay? Did he mean fuzz?" Listen, I get it. We wanted to start with a delay. Honestly, for a digital platform, it for sure is the most fun. A lot of fun, a lot of tears and a lot of breakdowns in designing the D1.

We learn a lot when we're at NAMM. We'd just come out with a stereo delay pedal, and the first thing after it is a mono reverb. I'm not dogging on mono reverbs. We love the Slö and the Fathom, but it's like, "Oh, shoot. Next year, we're going to have a reverb, so we don't have to have this weird signal chain thing." Reverb is for sure where we wanted to go next.

What also kind of sucks about NAMM is you've got to buy or borrow other people's stuff most of the time to really make the show work. We're knocking on Brian Ball's door like, "Hey, bro. We need 12 Music Mans." And he's so nice and lets us borrow 12 Music Mans. And we knock on Jim at Pedaltrain's door. We're like, "Yo. We need 12 Pedaltrains." And he's super happy to gift it and do all that kind of stuff. Then, at the same time, we are a no-amp zone at NAMM because we value our sanity. We'd been borrowing amp and cabinet simulators from really good companies up through last year. The one that spoke to us the most at all the trade shows was the Cabzeus from GFI. Then it was like, "Let's work extra hard this year and do our own amp/cab sim."

We pooled what we loved about the amplifier and cabinet simulators that we have played before and added new things that we wanted to have in our own. When I play stereo, I don't like bringing two Princetons; I like doing a Fender and a VOX. From the get-go, it was, "We are going to have independent left and right options on the amp/cab sim." So, you can get that charm of playing in stereo with a different sound in your left than your right; that fun saturation, that more expansive sound that comes from using two amps from two eras and two builders. The VOX and the Deluxe Reverb really go well together.

So that's how we decided on delay, reverb, and amp/cab sim for the MAKO Series so far. Next is for sure a high-end $400 preset-heavy buffer. [laughs]

Walrus Audio's R1 and ACS1 Prototypes

Pictured: Prototype Walrus Audio ACS1 and R1 pedals

Can you talk a little bit about how the ACS1 functions “under the hood?” 

Stulce: Think about an amp head and cab. Let's think about it that way because that's the two parts which are separate. You've got this "head" section of the pedal, which is algorithms, modeling the tubes, the transformer, the output transformer and other things like that. We looked at each amp and broke the circuit down to a very granular “block” level. Each one of those blocks is a step through a tube amp. We've got blocks of code that simulate each section. We string those together based on which amp we're talking about—Fender, Marshall, VOX.

We're able to simulate the response of each tube stage as well as the tone stack in the amp with the type of digital filtering that we're implementing. We also capture the tube saturation characteristics and the output transformer, which plays a big part in an amp's sound. That whole thing together creates one algorithm that's modeling the head portion of your guitar amp system.

That flows into an IR block that's loading these impulse responses, sort of like a digital thumbprint, of the cab part of the equation. After that, the sound of the amp going through a mic. If you were to take the output of the ACS1 straight to a console, it looks and sounds the same as if you put a guitar amp down and you put a mic in front of it. Think of that mic line as the output of the ACS1. You've got DSP modeling the amp itself, and you've got IR filtering taking care of the sound of the cabinet, speaker and microphone.

It's insane we did that, and a reverb and a new hardware platform all at the same time, all during COVID.

And all because of NAMM.

Stulce: And all because of NAMM, yeah.

Do you split the amp modeling to one processor and impulse responses to another? Is one tech better served for a function?

Stulce: Almost all of the audio processing is taking place in the SHARC. We're using a pretty sophisticated codec. A "codec" is a fancy word for analog/digital converter and a digital/analog converter all in the same chip. This chip takes care of getting audio in and out. This thing has a DSP core built into the codec itself, so we can do some pretty crazy stuff before we ever even get to the SHARC. Probably 95% of the audio processing or more is taking place in the SHARC, from the amp models through the IRs. What's pretty cool about the SHARC model that we're using, if we want to get real nerdy, is, it has a hardware IR accelerator built into it. So, we get to do the IR processing without really taking up a lot of bandwidth from the rest of the audio processing world, which is pretty fun.

How did you choose which amp models you'd use?

Stulce: For me, it's just three of my favorite amps. I'm a Tele guy, and I love playing Teles through Deluxes and AC30s. Playing them through Bluesbreakers is cool, too; it's just less my thing. I feel like it covers that chunky Marshall world pretty well. We wanted to cover a lot of ground with amps that we felt people were most familiar with.

Westbrook: We kind of had a fork in the road—when you do Marshall, you've got to go one way or the other. The Bluesbreaker was intentional in that we imagined people using the ACS1 more as a pedal platform amplifier. And that's the direction we wanted to take on the Marshall side. I'm really happy with how it turned out. I wish there were a more scientific answer like, "We polled 4,000 specific direct customers from our base…" but it just comes down to "We design stuff that we just really want to play."

The Deluxe Reverb, the AC30 and the Bluesbreaker are three of our favorite home bases. There are so many great amps out there, like the Benson Monarch Reverb or the Milkman Sound 20-watt Creamer, and not to say that we won't move into that space, but I think starting with the big three was where we wanted to be.

How did you settle on the exact physical example amps you used?

Stulce: It was about finding a solid representative for each type. We found both a vintage blueback and greenback AC30; both made in England. I really feel there's a difference there. It's kind of undeniable.

And then this Deluxe is super awesome. All original. Same thing with the Bluesbreaker. Just an old, made in England Bluesbreaker. And we went from there.

Westbrook: There's this guy in town. His name's Jaron Nix. He tracks all the audio for our full-band demos, tech demos and when we do "Songs at the Shop." He basically brings a whole studio here, and he's one of my favorite sound engineers in the Oklahoma City area. He had a lot of these amps within reach, and he helped Jason and me when we were doing the impulse response work.

Stulce: I spent a couple of days at his studio just with earplugs in. If you ever heard a sine [wave] sweep, 20Hz to 20kHz, that lasts 12 seconds long, that's loud. It's not fun. And that, times 80 or something, is what we did.

Tweaking the Walrus Audio ACS1

Pictured: A break in filming a video for the Walrus Audio ACS1

How do you approach having a Mid control while still staying true to the original amps' responsiveness? None of these three amps had Mid controls originally.

Stulce: We do a lot of thinking through, "How much do you want this to respond like the real amp, and how much do you want it to act as a pedal?" A lot of people haven't ever done a deep dive on an AC30. A lot of people have no clue how the tone stack works. So, there are some things—the tone stack is one of them, obviously—where we would try to get the general "fingerprint" of the amps, the sort of flat tone stack sound, but then allow a little further sculpting past what the knobs of the amp itself would do. Some of these amps, if not all, have a fixed mid-portion of the tone stack. You can mod these amps to create sort of a variable mid control, and that's in a way what we were doing with the mid knob on the ACS1—allowing additional tone shaping in a pretty approachable, intuitive way.

Westbrook: The whole banner of the Walrus R&D is "Timeless Sounds With Modern Innovations." So we're not trying to invent new sounds, but we're trying to add these timeless sounds into what the 2021 player is used to manipulating on the face of the pedal.

Can you talk about the different ways people can run the ACS1? What do you hear coming out mono versus stereo?

Stulce: You can run mono in and stereo out, or you can run stereo in and stereo out. And there are two completely independent paths in the pedal. So, there's no summing and operating on left and right signals in the same way, unless you choose that. But you have to make that choice.

What is the weirdest or “funnest” feedback you've gotten from players on the ACS1? 

Stulce: Probably the most fun for me, and this might sound strange, we had one guy describe it as sounding like beat-up old versions of the amps we were modeling. And that's exciting to me because what I hear there is they sound real. It doesn't sound perfect, because they don't sound perfect. You mic them up, and they're beat up. They're getting drug around in a car. If they're old, they're old. I mean, they've seen a lot of life. I don't think at all that means it sounds bad. He wasn't indicating that. He was indicating that it feels real. It sounded strange at first, but I liked it the more I thought about it. I realized what he was trying to say was they sound like amps. And that was the goal.

Westbrook: It was the goal. You see a lot of amp/cab sim demos, and a lot of the times, the players are doing heavy, wet effects and making big atmospheric sounds, or they're doing a lot of metal sounds, like, heavier things. We really want these to sound like amps. We don't want them to sound big when you turn pedals on. We want them to sound like amplifiers. Maybe that sounds stupid, but go back to our tech demo and our full-band demo. We intentionally ripped off Eagles and Zeppelin on the full-band demo because we wanted it to sound like amps. We didn't want to be like, "Here's our amp/cab simulator with a s*** ton of reverb." We just want it to sound like rock and roll. If you want to light a candle in your dorm room and have a reverb party by yourself, you totally can. But if you want to go have a rock-and-roll show and make it sound like amps, you can do that. Making sure they sound like amps. That was the whole idea.

I think we had slightly different college experiences.

Westbrook: In college, you know what I was doing? I was plugging my acoustic guitar up to—I had two [Line 6] DL-4s in my dorm room—because you know the Howie Day "Ghost" video went viral in college when YouTube was—I don't think it was even on YouTube—but Howie Day had this video. He was looping the "Ghost" beat and then playing it. We were all like, "Oh, my gosh." And then I was trying to do that in my dorm room for a long time. That's what I was doing. [laughs]

So, when you’re building out these models, do you make it sound like a new Bluesbreaker in 1966? Do you make it sound like a Bluesbreaker that has 50 years of component drift? How do you reconcile that with the expectation of the player?

Westbrook: You tell us.

Stulce: It's a good question. We set out to say, "We're not going to target this particular box sitting in front of us." We wanted to be inspired by, and be in the vein of, these amps, true to the essence of what these amps are and the sound they produce.

Personally, I'm not a splitting hairs guy. I don't know what you call this, but I'm all about, "You can split a ton of hairs, but then the second you put something in a mix, none of that matters anymore." And so that's not a cop-out, but it does steer where we put effort if that makes sense.

Westbrook: You can leave it to guys like Henning Pauly, HP42; he's going to do his demo video. He's going to compare the pedal with the actual amps for us and tell us if it sucks or if it's good. It's great. And we don't have to worry about it.

Stulce: I'm not trying to tell you that this is going to sound exactly like this amp sitting here with 400-volts DC running through tubes that are burning red hot. I mean, it's just not. It's supposed to be a tool to allow you to not have to bring that amp with you. And I think we did a good job accomplishing that. Am I going to sell my amps? Of course not. And I don't think anybody's buying this pedal thinking like, "Ooh, don't need that thing anymore." I'm still going to be playing through an amplifier, like any guitar player. I'm still going to want to play through an amplifier. So there are trade-offs. I mean, anybody that tells you otherwise is lying. I'm not trying to win you over. I think that there are people who appreciate the convenience and like the sound, and when it comes down to it, we talk about this all the time, but the tone's in your hands. You can take the worst you-name-it pedal, and the right person can make your jaw drop.

Hard to believe you didn't tap into the collective unconscious of every guitar player in the world in designing your amp and cab simulator. [laughter]

Westbrook: Should've. [laughs] I know. I just wrote that down. My favorite Instagram comment on the ACS1 said, "Oh, this is four years too late." I like to go on my personal account, and I like to engage and have a comment snack party. I was like, "Tell me what you mean." And he was like, "Amp/cab sims came out four years ago." And then I asked, "What about fuzz?" And he was like, "Even longer." I was like, "So people should stop making fuzz?" And he was like, "Never mind." [laughter]

Shifting to the R1, how does creating a reverb "sound" work inside of a digital pedal these days?

Stulce: You want to talk about some black magic.

Westbrook: Ones and zeroes, dude. It's all about ones and zeroes. Put them in the right order.

Stulce: There's a lot of ways to do it. And we could spend a ton of time talking about all the different ways. I'll just tell you how we approached it. I call them "meat and potatoes" sounds and "experimental, weird" sounds. That's the easiest way to describe it for me.

We took the approach from the "meat and potatoes" side of things to use impulse responses of spaces or devices, like the plate reverb. There are EMT-140 plate reverb impulse responses in that algorithm. There are spring tank impulse responses on the front end of the spring algorithm. There are hall capture impulse responses on the front end of the hall. It helps with the realism and getting the accuracy right on those algorithms. Those are coupled with diffusers on the end, which is the algorithmic way of lengthening the reverb sound. So it's like color and shape, the character of the sound feeding into this thing that allows us to drag it out really long if we want or filter it in different ways. All of that occurs after the IR.

In the more experimental algorithms, we use all sorts of combinations of all-pass filters, delay lines and many different types of filtering in various places in the algorithm to shape the reverb's sound.

Then, of course, you've got the whole modulation aspect and, depending on the algorithm, where and how it's employed. Is it used in just one spot or three spots? You're not just turning up depth on one little modulation block somewhere. That knob could turn up multiple different ratios of different aspects of modulation, whether in feedback loops or at the front end or all of them in different percentages. Sounds like Refract have even more additional sound elements, and Air has this sort of wind sound built into it.

Westbrook: [Makes wind noises]

Stulce: That thing. There's sound generation happening that's feeding the reverb, or maybe some of it is feeding it; some of it is manipulating the output, making it stutter or glitch. So yeah. You think about these different elements, understand them in a block diagram sense, and then string them all together. You enter into this cycle of iterating, and it's really about just where you're happy with it.

How do you put a restraint on yourself? How do you put the correct restraints on what the user can do to it?

Stulce: That's it. That's the whole thing. That is it. You covered all of it.

Westbrook: This is like an ideological conversation on where Walrus belongs. Where does EarthQuaker Devices belong? Where does TC Electronic belong? What's the lane that we play in on specific sounds? We strive for sounds that fit onto records that we all really like. If we're getting sounds that are huge and completely new and different, but they aren't already in our lane, we're going to have a tough time getting the customer base to trust us to say, "Hey, we're going to go over and play in this audio space for a second even though you don't know us for that, but we're going to go do it anyway." Not to say that we can't.

I mentioned EarthQuaker earlier; they have lots of different modulation reverbs with filters and exciting sounds that I hadn't heard until they came out with a certain pedal. For our take on reverb, we want to do a really good job with spring, hall and plate, and we wanted the other side of the R-1 to sound cinematic and to be a kind of soundscaping tool rather than a niche noise-making machine, where it could easily go.

For us, if it gets funny, then we'll take it out. Does that make sense? If it gets like, "That's a funny sound," we'll take it out. Not to say that funny sounds aren't allowed. They're great, and I have a lot of records where I love them, but for us, if it can go on a record, it should go in a pedal.

Are you staying exclusively in the guitar world as you test designs? 

Stulce: We've experimented with synths. We use them as we're working on development now and then. We've typically stayed pretty focused on the guitar world. From the technical side of things, to do a synth pedal right or a pedal that is great with synths, you kind of have to rework a lot of the analog side of things. It's a bit different than a standard guitar pedal. Up to this point, we've stayed pretty true to that guitar lane.

For sure, it's something that's on our minds, doing pedals that are more geared from the ground up for keys players or more geared from the ground up for bass players. There are definitely things that should be done for those avenues that we wouldn't necessarily have to do or need to do for the guitar lane.

Building a Walrus Audio R1 Pedal

Pictured: Building a Walrus Audio R1

What do you think of some people only knowing a digital pedal experience?

Stulce: I think, if anything, it'll circle back. I think we'll swing super far [towards] digital in the same way that amps did. Then it all swung back to tube. I wonder if that'll happen again in the pedal world.

Westbrook: That's how life goes. It will. You'll get analog purists in 15, 20 years coming back saying, "No. You guys are missing out. The digital world is better than ever."

Stulce: I play four times a week at a venue, and I experimented on myself. I used a particular piece of gear, which will go unnamed, in place of all my gear except my guitar. You might be able to guess what this is. But my point is, I did that for a year, and it was to feel the difference, to feel the other side of things. And I was pretty fine with it, to be honest, for what I do.

Toward the end of my test, I started getting this itch again. I was getting tired of it. What I realized is I was tired of it being so easy. I missed a patch cable shorting out; I missed the chase, the creative part of the pedalboard. The palette and recipe for building sounds. I missed all of that.

So, I ended up going back, and it was like, "Man, I get it. I get it again." And it was this refreshing moment when I switched back over. It was a little intimidating, but I think people will go through that cycle for themselves over time. The masses will, and it'll be cool again to play with analog gear/pedals versus an all-in-one, super-sleek digital boxes.

Westbrook: It's like there are Leatherman and Swiss Army knife people. And they love—and there's nothing wrong with it—but they love, "Man, I got a corkscrew. I got a toothpick. I got a Philips head. I got a sawblade."

Stulce: Scissors.

Westbrook: "I got scissors." But then some people are just like, "I need a knife. I just need a knife." And that's just what we are. We're not Swiss Army knife guys. We're not Leatherman guys. We just need a knife, a really good knife to do the job, [holds up knife] as I'm holding my Kershaw Blur blade. It's just a knife. It does the job.

Stulce: Weird flex, but okay.

Westbrook: Seriously. It opens boxes super well, and sometimes it opens the mail, and that's all I want it to do. I don't want to carry a Leatherman around. But some people do, and they love that there are those options available. We're just not good at getting into that mental space. That's just not who we are in our souls, and so we wouldn't make a good all-in-one box like that.

Stulce: I think people would get bored.

Walrus Audio's Colt Westbrook and Jason Stulce

Pictured: Colt Westbrook and Jason Stulce

What do you foresee as the future of the MAKO series?

Westbrook: I think two things. You go ahead, Jason.

Stulce: I've already mentioned a fundamental thing,, with users being able to update firmware—that's a new world. There's a lot of complexity and work that comes along with that, but being able to offer that and do that well is something that I think users can look forward to. And maybe not even just the MAKO series. Maybe past that. We'll see, but that's certainly one thing.

As we see the platform grow and get into peoples' hands, we'll start to flesh out what a next generation might look like, or feel like, or do. Maybe some different effects or I/O that makes more sense for particular effects than what's on there now. So, you may see some changes in that regard. And then possible form factor changes. I don't see anything past that, but yeah. And expanding of the line.  


Westbrook: I hate reading manuals, and so if I get a product out of the box and I have to read a manual, I'm going to sell it. If I have to read this whole damn book to understand this guitar pedal or this piece of gear, I don't want to do that.

Stulce: You can see where our brains differ—I go technical and he goes philosophical every time, which is great. That's super awesome.

Looking to the future, do you envision a time that there's Walrus Audio plug-ins or Walrus Audio 500-series?

Westbrook: I think it goes back to trust—there are two ways you can go. It's like, we're either going to develop the new platform and bring a new customer group onboard, or we're going to develop a new platform and bring our existing customer group onboard with that. It really goes into trust. Why is your new or existing customer group going to trust that you're now doing plug-ins?

With pedal companies, if you're going into the 500-series space, you're stepping into the studio space. Other companies have been there for decades. You've got to do it the right way because you're going to go play with the pros. It's like, [just because] you've done well in the pedal space, doesn't necessarily give you license to go rule and reign in the studio space. It's a completely different ground-up philosophy for the most part.

And so, if you're going to do that, you've got to go in a way that people are going to trust what you're going to do. Plus, the final product has to contend with what already exists.

If we're going to go into plug-ins which, you know, honestly, we'd love to, there has to be a reason why it exists instead of the never-ending, “Who can make the best Tube Screamer?” Well, we're going to stay out of that fight because there's already a lot of great ones.

But I think when you're thinking of new platforms and new spaces, you got to have the "Why does it exist?" and then, "Who is it for?" And then from there, you can go. And then you'll fail a lot of the time. And then sometimes, you'll win. So, we'll see.

Stulce: It's super easy to do something just to do it. It's incredibly difficult to do it with purpose and do it real and do it well. And so, I would hope we stay in a spot where we're only doing things that we have a real passion and desire to do that far surpasses another new product or an expansion of the business. We don't really operate like that. I'm going to fight to keep it meaningful and within our core focus.

We talk a lot about that internally, making sure that we weigh tons of ideas. A lot of them are good, but we throw a lot of them out because it's like, "Well, I don't think that's in our core focus." So, I'd rather do what we do really well. If something down the road makes sense for us to expand, we're not going to do that until we can do it well with a real good reason to do it.

Westbrook: We also, asterisk, do have a TS-style overdrive, and it is the Warhorn. I bashed on who can make the best Tube Screamer. But then I was like, "Someone's going to be reading and be like, ‘that a-hole, he's got the Warhorn’," and that's—all right. Yeah, yeah. I get it. I get it. [laughter]

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